The principal Investigator, Dr. Qin, has the long-term goal of pursuing independent investigation in the field of steroid hormone biosynthesis and its regulation in human ovary. A Mentored Clinical Scientist Development Award will facilitate the growth of Dr. Qin's investigative skills and experience by expanding his knowledge of clinical, molecular, and immortalized celli lines or transgenic techniques through clinical research, technical training, and formal course work, as outlined in the proposed studies. The combination of his learning objectives, the support of his Mentor, Dr. Robert Rosenfield, and Advisors, Drs. Sally Radovick and Samuel Refetoff, and the rich research environment at The University of Chicago, will foster Dr. Qin's progression to independent lines of investigation. The Specific Aims of this proposal will extend earlier inquiries by Dr. Qin into factors important for the regulation of testosterone production by theca cells, a specific type of hyperandrogenism in PCOS, and establishment of theca cell lines for further studies. Three aims are defined: 1) To study the regulation of 17beta-HSD5in theca-interstitial cells. To characterize the molecular mechanisms involved in tissue-specific regulation of the 17beta-HSD5gene, specific deletions of the human 17beta-HSD5promoter will be ligated into a promoterless luciferase expression vector, and reporter constructs will be transiently transfected into theca cells. The basal promoter element and the elements involved in LH, FSH, and insulin-dependent regulation of the human 17beta-HSD5gene will be monitored by luciferase activities. 2) To study the relationship of 5'-UTR variants of the human 17beta-HSD5 gene to a specific phenotype of hyperandrogenism in women. GnRH agonist and ACTH testing will be used to identify a type of hyperresponsive testosterone synthesis in PCOS and relate it to sequence variants of the 17beta- HSD5 promoter, starting with a G/G-71 variant. 3) To generate and characterize immortalized theca cell lines by stable transfection with a temperature-sensitive SV40 large T antigen gene. Clonally derived theca cell lines will be developed which have the capacity for steroid biosynthesis in response to LH. This award will dedicate these five years to rigorous scientific, technical, and intellectual training such that Dr. Qin can ultimately develop into an independently productive physician-scientist.